Multirange receiver



sein. 2s, 1937.

w. VAN B. ROBERTS MULIIRANGE RECEIVER Filed 001'?. 26', 1935 IMU' BY l INVENTOR RUM/W5 ATToRNEY Patented Sept. 28, 1937 UNITED sTATEs PATENT OFFICE MULTIRANGE RECEIVER yWalter van B. Roberts, Princeton, N. J., assignor to Radio Corporation of America, `a corporation of Delaware Application October 26, 1933, Serial No. 695,224

Claims. (Cl. Z50-40) My present invention relates to radio receivers, and more particularly to an improved tuning means for multi-range receivers.

- A multi-range receiver as employed in the present invention indicates a receiver which is capable of receivingsignals over a very vvidey range of frequencies, such as 20,000,000 cycles. In such a multi-range receiver there is usually employed Y a switching means for selecting particular narrow y"bands within the complete range of thereceiver. SinceV the widest audio channel is only about 10,000 cycles wide, there may be some 2,000 different adjustments in a frequency range of megacycles, any one of which might be correct for reception of a station. To successively tune The receiver in the accompanying drawing is 15 the receiver to each of these 2,000 different adshown as of the tuned radio frequency amplifier justments in the search for a signal of unknown type, but it is to be clearly understood that it may frequency is la tedious job, even if the receiver be'of the superheterodyne type. 'I'he signal'colis designed to permit of the simplest uni-control lector A is the customary grounded-antenna ciroperation. The reason for this: is that if the cuit,'but it may be replaced by a radio 'distribu-4 20 rangevis covered in too short a time, the station tion system, or it may be a loop antenna; The hunted for would be passed over too quickly to rst tube I, of the screen grid type, has its input notice. i v electrodes connected across the variable resistor n Accordingly, it is one of themainy objects of 2,` the latterbeing arranged in series in the an,- the present invention to-tune through a plurality tenna circuit. The resistor 2 functions as a man- 25 of tuning bands of a very wide vfrequency range ual volume control element, but it is to be undersimultaneously, and to provide a means for renstood-that any other well known type of amplifier dering the receiver simultaneously sensitive to output 'control device may be employed. allof such tuning bands, there being means for `'I'he anode circuit of tube I includes a pluralityY rendering the receiver insensitive to all but one of coils arranged in series relation. For illusof said bands. Y' Y trative purposes three such coils 3, 4 and 5 are Another l object ofthe present invention is to shown arranged in series between the anode of provide `a multi-range receiver which is adapted tube I and the positive side of the usual potento cover a-very wide frequency range in a simple tial source B. These coils are the primary coils and efcient manner, the receiver being provided of radio frequency coupling transformers, whose with a plurality of networks including cascaded secondaries are coils 3', 4 and 5' respectively. resonant circuits, each networkv being'tunable The secondary coils are arranged in seriesbethrough a predetermined band of the very'wide tween the control grid of screen grid tube 6 and frequency range, and each circuit cfa network ground. lVariable tuning condensers 1, 8 and 9 being provided with a switch for selectively conare connected across coils 3', 4 and 5 respecnecting or disconnecting the associated circuit tively. Each of these tuning condensers is confrom a given amplier structed with respect to its associated coil to tune Still another object of the invention may be its resonant circuit over a predetermined 'fre-v stated to reside in the provision in a multi-range quency band of the multi-band frequency rangey receiver of aplurality of ycascaded amplier tubes,l of the receiver. The amplifier tubeA E has its 45 and a coupling network between each pair of succathode grounded through the usual grid bias cessivetubes, which includes a plurality of resonetwork IIJ, while its anode` is connected to a nant circuits, each resonant circuit being adaptpoint on source B of appropriate positivepotenedto be tuned through a different tuningband vtialf of theentire frequency range, there additionally A switch is arranged in shunt with each of being provided switches in each network for secondensers 'I, S and 9, and these switches funclectively eliminatingone or more of its degrees tion to selectively render amplifier 6 insensitive of freedom. for a desired one of the tuning bands correspond- Still other objects of `the invention are to iming tothe resonant circuits connected in the grid prove generallythe simplicity and efficiency of circuit of the amplier tube 6. Thus,'the open- 5,5.

by reference to the following descriptionftaken;1

in connection with the drawing, in which I have provide I V indicated diagrammatically a circuit organization'whereby my invention may be carried into effect.

ing of switch II, and the closing of switches I2 and I3 renders the amplier 6 sensitive `solely for those frequencies lying within the tuning range of the band over which the resonant circuit including condenser 'I is operative. By virtue of the closing of switches I2 and I3 the amplier 6 is insensitive to the frequencies lying within the bands corresponding to the resonant circuits including condensers 8 and 9. yFor the purpose of reference, switch II has been designated in the drawing as controlling the operation within a band A, while switch I2 controls operation in band B, and switch I3 controls operation in band C. It is to be understood that these three bands may be adjacent, spaced, or even overlapping. Furthermore, each of these bands may have a frequency coverage which is relatively wide or relatively narrow.

The screen grid tube 6', following the tube 6, is shown as being arranged for functioning as a detector. The grounded cathode circuit of the tube 6 includes a grid biasing network I0', and those skilled in the art will understand that the constants of this network are so chosen that the tube 6 functions as a bias detector by virtue of plate rectification. The circuit between the anode of'tube 6 and the grid of tube 6' is a duplicate of the circuit between the anode of tube I and the grid of tube 6. Thus, there is arranged in the anode circuit of tube 6 the three primary coils which correspond to the primary coils 3, 4 and 5. Each of these primary coils is coupled to a secondary coil in the same manner as in the case of secondary coils 3', 4' and 5. Again, the tuning condensers 1, 8 and 9 connected across the secondary coils in the grid circuit of tube 6 are similar to the condensers l, 8 and 9 respectively. Additionally, the switches II, I2 and I3 nd their counterparts II, I2 and I3 in the resonant circuits arranged in the grid circuit of tube 6.

The dotted line 20 is to be understood as illustrating a conventional mechanical coupling between the switches II and II, so that these two switches may be opened and closed simultaneously. Dotted line 20' illustrates the mechanical coupling between the switches I2 and I2', while the dotted line 2l represents the mechanical coupling between switches I3 and I3. The tuning condensers I and I' have their rotors arranged for uni-control adjustment, and this mechanical adjustment is represented by the dotted line 30. The variable condensers 8 and 8 are shown arranged for mechanical uni-control, and the uni-control is represented by the dotted line 30. The Variable tuning condensers 9 and 9' are shown arranged for mechanical uni-control by the dotted line 3|. Finally, the ganged tuning arrangements of bands A, B and C are shown arranged for simultaneous control, and this mechanical coupling between the gangs of condensers is represented by the dotted line 32. The common operating knob for the plurality of tunisng bands is designated by the reference numeral The anode of the detector tube 6' is connected to a point on source B of appropriate positive potential through the primary of the audio frequency coupling transformer 40. It is to be understood that the transformer d connects the anode circuit of detector tube 6 to one, or more, succeeding stages of audio frequency ampliication, and/or a reproducer of the electrodynamic or electromagnetic type. As stated heretofore, the present arrangement is not conned in its usage to a receiver of the tuned radio frequency amplier type, but may be embodied in a superheterodyne receiver. In such a case, the tube 6 could Well be the rst detector tube of the superheterodyne receiver.

The operation of the arrangement embodying the present invention should now be readily understood from the aforegoing detailed description and the accompanying drawing. 'Ihe present invention contemplates the tuning of a radio receiver through a plurality of tuning bands of a predetermined frequency range simultaneously. For example, suppose there are ten such tuning bands, each 200 channels wide. Then, if the knob 33 is actuated, the search for a given signal irequency goes on simultaneously in each of these tuning bands, and the time required for searching the entire frequency range is reduced to onetenth. Once a station is heard, the receiver may be rendered insensitive to all of the tuning bands other than the one in which the station lies. In the specific case shown in the drawing, when all the switches of each tuning band are open, the receiver will respond to any signal lying within any of the three tuning bands A, B and C, By closing switches I2 and I2', for example, the receiver becomes insensitive to the tuning band B. In operation, once a station is heard, and assuming that the station lies in band A, switches I2 and I2 and I3 and I3 will be closed. 'I'he closing of theselatter switches minimizes interference, and renders the receiver sensitive only to the tuning band A. The particular mechanical coupling of the three condenser gangs is immaterial to= the present invention. A belt, or any well known type of link coupling, may be utilized between the knob 33 and the mechanical couplings 30, 30 and 3|.

The essential feature of the invention is to provide a receiver which is simultaneously sensitive to a plurality of frequencies specifically lying in different tuning bands, the receiver additionally including means for tuning it through these different tuning bands, and the receiver finally including means for rendering it insensitive to all but one of a desired frequency of a given tuning band.

While I have indicated and described a system for carrying my invention into eifect, it will be apparent to one skilled in the art that my invention is by no means limited to the particular organization shown and described, but that many modifications may be made without departing from the scope of my invention, as set forth in the appended claims.

What I claim is:

1. In a radio receiver including at least two cascaded tubes, a coupling network between said tubes comprising a plurality of resonant circuits connected in series between the input electrodes of the second tube, means in each of said circuits for tuning its associated circuit through a predetermined tuning range, said tuning ranges being different, a single means for simultaneously adjusting said tuning means throughout said ranges, and additional means for rendering ineflicient the transmission between any one of Said circuits and said second tube.

2. In a radio receiver including at least two cascaded tubes, a coupling network between said tubes comprising a plurality of resonant circuits connected in series between the input electrodes of the second tube, means in each of said circuits for tuning its associated circuit through a predetermined tuning range, said tuning ranges being different, a single means for simultaneously adjusting said tuning means throughout said ranges, and additional means including a switch in each 0f said circuits for rendering inefficient the transmission between any one of said circuits and said second tube.

3. In a radio receiver including at least two cascaded tubes, a coupling network between said tubes comprising a plurality ofv resonant circuits connected in series between the input electrodes of the second tube, means in each of said circuits for tuning its associated circuit through a predetermined tuning range, said tuning ranges being different, a single means for simultaneously adjusting said tuning means throughout said ranges, additional means including ,a switch in each of said circuits for rendering ineflicient the transmission between any one of said circuits and said second tube, a third tube following said second tube, and a coupling network between said second and third tubes which is similar in construction to said first named coupling network.

4. In a radio receiver including at least two cascaded tubes, a coupling network between said tubes comprising a plurality of resonant circuits connected in series between the input electrodes of the second tube, means in each of said circuits for tuning its associated circuit through a predetermined tuning range, said tuning ranges being different, a single means for simultaneously adjusting said tuning means, additional means for rendering ineiiicient the transmission between any one of said circuits and said second tube, a third tube following said second tube, a coupling network between said second and third tubes including resonant circuits similar in construction to said resonant circuits of the first coupling network, and means mechanically coupling the tuning means of corresponding resonant circuits of said first and second coupling networks whereby said tuning means are adjustn able by said adjusting means over said ranges.

5. A radio receiver including an amplifier provided with a plurality of tunable circuits in its input circuit, a single means for simultaneously Varying the tuning of each of said circuits over a frequency range different from that of every other tunable circuit, said amplier being simultaneously sensitive to the frequencies in each of said tunable circuits, and means for rendering said amplier insensitive to all but one of said tunable circuits.

6. A multi-range receiver comprising a vacuum tube device, a plurality of tunable circuits serially connected to the input of said device, each tunable circuit being resonant to a different predetermined brand of a plurality of frequency bands which comprise the range of the receiver, separate means for tuning each of said tunable circuits, and separate means for shortcircuiting each of said circuits.

'7. The invention dened in claim 6 wherein ythe vacuum tube device comprises a radio frequency amplier.

8. The invention dened in claim 6 wherein the vacuum tube device comprises a detector.

9. A multi-range receiver comprising a radio frequency amplifier, a detector, a plurality of series-connected tunable circuits connected to the input of the amplier, a similar set of tunable circuits connected to the input of the detector, corresponding tunable circuits of the amplifier and detector being resonant to a diiferent predetermined band of a plurality of frequency bands which comprise the range of the receiver, separate means for tuning each of said tunable circuits, and separate means for short-circuiting each of said circuits.

10. A multi-range receiver comprising a radio frequency amplifier, a detector, a plurality of series-connected tunable circuits connected to the input of the ampliiier, a similar set of tunable circuits connected to the input of the detector, corresponding tunable circuits of the amplifier and detector being resonant to a different pre determined band of frequencies within the range of the receiver, separate means vfor tuning each of said tunable circuits, means for controlling in unison the operation of all said separate tuning means, separate means for short-circuiting each of the tunable circuits, and means for controlling in unison the operation of the separate shortcircuiting means associated with the tunable circuits of the amplier and detector which are resonant to the same frequency band.

WALTER VAN B. ROBERTS. 

